长江三峡水轮发电机组参数选择的几个问题及建议

Problems and Suggestions Concerning the Parameter Selection of Turbine Generating Set for Three Gorges Project at Yangtze River

长江三峡水电站是世界上在建的最大水电站。水轮机水头变幅大；汛期低水头运行；枯期高水头运行时间长；对水轮机性能要求高，水轮发电机组参数选择难度大。根据三峡电站的特点建议：（１）、尽可能选择较大直径的水轮机，增大低水头过流能力，汛期多发电能；（２）、发电机应设一个８３０ＭＶＡ以上的最大容量，以扩大水轮机在高水头时的运行范围，提高稳定性；（３）、初期投入的６台机组使用初期转轮，库水位提高后更换永久转轮，可获得显著经济效益；（４）、２００５年后投运的机组，水轮机按后期水头范围设计，其设计水头可按比电能加权平均水头更高的电能价值加权平均水头考虑，以改善高水头运行的稳定性，并提高效率。

The Three Gorges Project at Yangtze River is the biggest hydropower station under construction in the world. The amplitude range of water head applied to the turbine is rather wide,thereby turbines have to operate at low head during the flood season While at high head during the dry season. It is strict with the turbine performance. Naturally,parameters of turbine generating set are difficult to select with. The authors express their opinions on the characteristics of this project as follows:first,to select turbine with larger diameter as mush as possible,then its discharge capacity strengthened and generating capacity increased during the flood season;second, a largest capacity of over 830MVA must be provided for the generator to enlarge its operating limit at high head and to raise its stability;third,in the early stage, 6 runners for innal use but change them for permanent ones afterwards when the reservoir level has raised high enough, thus the obvious economic results can be obtained; fourth, turbine of unit commissioned after 2005 should be designed within the range of late water head, the design head can be considered as the one based on the weighted average energy value which is more than that based on the weighted average energy,so the operating stability at high head can be improved and the benifit increased hence.